During the last ten to fifteen years the use of tool attachment systems for the rapid change of buckets and tools with regard to excavating machines, wheel-mounted loaders, material handling machines of several different types have been a matter of course in the majority of European markets. The development of such systems has quickly advanced from simple mechanical solutions in which the driver leaves the driver's cabin and releases or locks the tool attachment mechanism with the aid of a simple movement of a lever and manually connects the working hydraulics of the tool. This solution has gradually been replaced with hydraulic solutions in which the driver is able to control a locking cylinder that actuates the attachment locking mechanism, by simply pressing a button in the driver's cabin. Although the tool is quickly connected mechanically in this latter case, it is still necessary to connect the hydraulic hoses to the hydraulic tool by hand. In recent years there have also been used fully automatic tool fastening systems. One example of such systems is described for instance in EP 483 232 and EP 602 165. In these cases mechanical and hydraulic buckets and tools are coupled and released fully automatically directly from the driver's cabin. Hydraulic hoses and electric supply lines are also coupled fully automatically in these cases.
The solutions described above apply generally to all types of tool carriers. For the sake of simplicity, however, the following text will be concentrated on the tool attachments for wheel-carried loaders.
The system solutions relating to fully automatic tool attachment solutions have become more complex and a number of sub-functions have been proposed in an endeavor to achieve fully functional solutions, namely:                a) A hose fracture function which is normally fitted directly to the locking cylinder to ensure that the locking function of the attachment will function even in the event of a hose fracture on the hydraulic hoses leading to the locking cylinder.        b) An electricity reversing function. In conjunction with the hydraulic rapid tool attachment the most usual solution applied involves the installation of an electricity reversing valve, a type 6/2 valve, in order to lend oil from the normal tool hydraulic system to the locking function of the attachment locking pistons. This magnetic valve is controlled electrically via a low voltage cable and a contact breaker in the driver's cabin. The reversing valve is normally placed on the machine, on its arm or jib, or separately on the tool attachment. By placing the valve as close as possible to the locking cylinder, it is possible to reduce the length of the hydraulic hose for the locking function. The valve is usually placed on the tool attachment, although this incurs serious mounting problems, especially in the case of smaller machines, due to the highly confined space available to this end. The extension of the hose between the valve and the locking cylinder presents another problem.        c) Post tensioning of the locking function in the above solution via the reversing valve. When the locking hydraulics is released with the aid of an el-type reversing valve the locking cylinder will not be subjected to any post-tensioning pressure when the valve is short circuited to the other function to give working hydraulics. The post tension on the locking system can thus be solved with a separate arrangement, in which a so-called bypass line that includes a check valve is drawn between tool hydraulics and the working hydraulics. See the following hydraulic diagram. This is usually solved by placing a hose loosely on the tool attachment. WO 2004/067855 describes a valve solution in respect of the quick attachment of a krans, where said post-tensioning function is included in a separate valve block. It will be noted that this block is not connected directly to the cylinder but is, instead, connected via hydraulic hoses.        d) The load is relieved automatically prior to connecting and disconnecting the tool hydraulics. This enables the pressure in the hoses leading to the tool hydraulics to be eliminated so as to enable the hydraulics to be released in the absence of pressure. This is particularly important in connection with fully automatic attachment systems, so that the seals in the quick couplings will be protected. This automatic pressure relief is normally effected on the machine by installing leakage lines from the tool hydraulics that are connected directly to a tank via a dumping valve. The dumping valve is controlled automatically from the attachment locking hydraulics and is provided with a time relay which ensures that the tool hydraulics are relieved of pressure prior to connection and disconnection.        
All of these sub-functions are normally installed separately on the machine, the excavating/lifting arm or on the tool attachment. This installation is normally carried out in the aftermarket and is expensive and complicated since it is often necessary to loosen these parts individually from case to case and since these parts are tailored separately for the machine concerned. Moreover, several parts are included in the various solutions, in the form of machine suppliers, tool suppliers or attachment suppliers. In the majority of cases this will result in an obscure distribution of responsibility between the parties concerned.